Contract Name:
SingleStaking
Contract Source Code:
// SPDX-License-Identifier: MIT
// Reference: copied from https://github.com/sushiswap/sushiswap/blob/canary/contracts/MasterChefV2.sol
// Reference: https://github.com/sushiswap/sushiswap/blob/canary/contracts/MiniChefV2.sol
pragma solidity >=0.8.4;
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/Multicall.sol";
import "./interfaces/IRewarder.sol";
import "./libraries/SafeMath.sol";
import "./libraries/SignedSafeMath.sol";
// @notice Staking contract to reward Tokens for stakers
contract SingleStaking is Ownable, Multicall {
using SafeMath for uint256;
using SafeMath128 for uint128;
using SafeERC20 for IERC20;
using SignedSafeMath for int256;
/// @notice Info of each stakers.
/// `amount` LP token amount the user has provided.
/// `rewardDebt` The amount of Token entitled to the user.
struct UserInfo {
uint256 amount;
int256 rewardDebt;
}
// The amount of RewardToken entitled to a user but is pending to be distributed is:
//
// pending reward = (user.amount * pool.accRewardPerShare) - user.rewardDebt
//
// Whenever a user deposits or withdraws LP tokens to a pool. Here's what happens:
// 1. The pool's `accRewardPerShare` (and `lastRewardBlock`) gets updated.
// 2. User receives the pending reward sent to his/her address.
// 3. User's `amount` gets updated.
// 4. User's `rewardDebt` gets updated.
/// @notice Info of each Staking pool.
/// `allocPoint` The amount of allocation points assigned to the pool.
/// Also known as the amount of Token to distribute per block.
struct PoolInfo {
uint128 accRewardPerShare;
uint64 lastRewardBlock;
uint64 allocPoint;
}
/// @notice Address of Reward Token contract.
IERC20 public immutable rewardToken;
/// @notice Info of each Staking pool.
PoolInfo[] public poolInfo;
/// @notice Address of the LP token for each Staking pool.
IERC20[] public lpToken;
/// @notice Address of each `IRewarder` contract in Staking.
IRewarder[] public rewarder;
// @notice reward owner address which owns reward tokens
address public rewardOwner;
/// @notice Info of each user that stakes LP tokens.
mapping(uint256 => mapping(address => UserInfo)) public userInfo;
/// @dev Total allocation points. Must be the sum of all allocation points in all pools.
uint256 public totalAllocPoint;
uint256 public blockReward;
uint256 private constant ACC_PRECISION = 1e12;
event Deposit(address indexed user, uint256 indexed pid, uint256 amount, address indexed to);
event Withdraw(address indexed user, uint256 indexed pid, uint256 amount, address indexed to);
event EmergencyWithdraw(address indexed user, uint256 indexed pid, uint256 amount, address indexed to);
event Harvest(address indexed user, uint256 indexed pid, uint256 amount);
event LogPoolAddition(uint256 indexed pid, uint256 allocPoint, IERC20 indexed lpToken, IRewarder indexed rewarder);
event LogSetPool(uint256 indexed pid, uint256 allocPoint, IRewarder indexed rewarder, bool overwrite);
event LogUpdatePool(uint256 indexed pid, uint64 lastRewardBlock, uint256 lpSupply, uint256 accRewardPerShare);
event LogInit();
event LogBlockReward(uint256 blockReward);
/// @param _rewardToken The reward token contract address.
/// @param _blockReward Initial Token Reward per block.
constructor(IERC20 _rewardToken, address _rewardOwner, uint256 _blockReward) public {
rewardToken = _rewardToken;
blockReward = _blockReward;
rewardOwner = _rewardOwner;
}
/// @notice Sets the reward owner.
function setRewardOwner(address _rewardOwner) public onlyOwner {
rewardOwner = _rewardOwner;
}
/// @notice set block reward.
function setBlockReward(uint256 _blockReward) public onlyOwner {
massUpdatePools();
blockReward = _blockReward;
emit LogBlockReward(_blockReward);
}
/// @notice Returns the number of Staking pools.
function poolLength() public view returns (uint256 pools) {
pools = poolInfo.length;
}
function checkPoolDuplicate(IERC20 _lpToken) public {
uint256 length = lpToken.length;
for (uint256 pid = 0; pid < length; ++pid) {
require(lpToken[pid] != _lpToken, "Staking: existing pool");
}
}
/// @notice Add a new LP to the pool. Can only be called by the owner.
/// DO NOT add the same LP token more than once. Rewards will be messed up if you do.
/// @param allocPoint AP of the new pool.
/// @param _lpToken Address of the LP ERC-20 token.
/// @param _rewarder Address of the rewarder delegate.
function add(
uint256 allocPoint,
IERC20 _lpToken,
IRewarder _rewarder
) public onlyOwner {
checkPoolDuplicate(_lpToken);
uint256 lastRewardBlock = block.number;
totalAllocPoint = totalAllocPoint.add(allocPoint);
lpToken.push(_lpToken);
rewarder.push(_rewarder);
poolInfo.push(
PoolInfo({ allocPoint: allocPoint.to64(), lastRewardBlock: lastRewardBlock.to64(), accRewardPerShare: 0 })
);
emit LogPoolAddition(lpToken.length.sub(1), allocPoint, _lpToken, _rewarder);
}
/// @notice Update the given pool's Reward token allocation point and `IRewarder` contract. Can only be called by the owner.
/// @param _pid The index of the pool. See `poolInfo`.
/// @param _allocPoint New AP of the pool.
/// @param _rewarder Address of the rewarder delegate.
/// @param overwrite True if _rewarder should be `set`. Otherwise `_rewarder` is ignored.
function set(
uint256 _pid,
uint256 _allocPoint,
IRewarder _rewarder,
bool overwrite
) public onlyOwner {
massUpdatePools();
totalAllocPoint = totalAllocPoint.sub(poolInfo[_pid].allocPoint).add(_allocPoint);
poolInfo[_pid].allocPoint = _allocPoint.to64();
if (overwrite) {
rewarder[_pid] = _rewarder;
}
emit LogSetPool(_pid, _allocPoint, overwrite ? _rewarder : rewarder[_pid], overwrite);
}
/// @notice View function to see pending Rewards on frontend.
/// @param _pid The index of the pool. See `poolInfo`.
/// @param _user Address of user.
/// @return pending Token reward for a given user.
function pendingRewards(uint256 _pid, address _user) external view returns (uint256 pending) {
PoolInfo memory pool = poolInfo[_pid];
UserInfo storage user = userInfo[_pid][_user];
uint256 accRewardPerShare = pool.accRewardPerShare;
uint256 lpSupply = lpToken[_pid].balanceOf(address(this));
if (block.number > pool.lastRewardBlock && lpSupply != 0) {
uint256 blocks = block.number.sub(pool.lastRewardBlock);
uint256 rewards = blocks.mul(blockReward).mul(pool.allocPoint) / totalAllocPoint;
accRewardPerShare = accRewardPerShare.add(rewards.mul(ACC_PRECISION) / lpSupply);
}
pending = int256(user.amount.mul(accRewardPerShare) / ACC_PRECISION).sub(user.rewardDebt).toUInt256();
}
/// @notice Update reward variables for all pools. Be careful of gas spending!
function massUpdatePools() public {
uint256 length = poolInfo.length;
for (uint256 pid = 0; pid < length; ++pid) {
updatePool(pid);
}
}
/// @notice Update reward variables of the given pool.
/// @param pid The index of the pool. See `poolInfo`.
/// @return pool Returns the pool that was updated.
function updatePool(uint256 pid) public returns (PoolInfo memory pool) {
pool = poolInfo[pid];
if (block.number > pool.lastRewardBlock) {
uint256 lpSupply = lpToken[pid].balanceOf(address(this));
if (lpSupply > 0) {
uint256 blocks = block.number.sub(pool.lastRewardBlock);
uint256 rewards = blocks.mul(blockReward).mul(pool.allocPoint) / totalAllocPoint;
pool.accRewardPerShare = pool.accRewardPerShare.add((rewards.mul(ACC_PRECISION) / lpSupply).to128());
}
pool.lastRewardBlock = block.number.to64();
poolInfo[pid] = pool;
emit LogUpdatePool(pid, pool.lastRewardBlock, lpSupply, pool.accRewardPerShare);
}
}
/// @notice Deposit LP tokens to Staking contract for Reward token allocation.
/// @param pid The index of the pool. See `poolInfo`.
/// @param amount LP token amount to deposit.
/// @param to The receiver of `amount` deposit benefit.
function deposit(
uint256 pid,
uint256 amount,
address to
) public {
PoolInfo memory pool = updatePool(pid);
UserInfo storage user = userInfo[pid][to];
// Effects
user.amount = user.amount.add(amount);
user.rewardDebt = user.rewardDebt.add(int256(amount.mul(pool.accRewardPerShare) / ACC_PRECISION));
// Interactions
IRewarder _rewarder = rewarder[pid];
if (address(_rewarder) != address(0)) {
_rewarder.onTokenReward(pid, to, to, 0, user.amount);
}
lpToken[pid].safeTransferFrom(msg.sender, address(this), amount);
emit Deposit(msg.sender, pid, amount, to);
}
/// @notice Withdraw LP tokens from Staking contract.
/// @param pid The index of the pool. See `poolInfo`.
/// @param amount LP token amount to withdraw.
/// @param to Receiver of the LP tokens.
function withdraw(
uint256 pid,
uint256 amount,
address to
) public {
PoolInfo memory pool = updatePool(pid);
UserInfo storage user = userInfo[pid][msg.sender];
// Effects
user.rewardDebt = user.rewardDebt.sub(int256(amount.mul(pool.accRewardPerShare) / ACC_PRECISION));
user.amount = user.amount.sub(amount);
// Interactions
IRewarder _rewarder = rewarder[pid];
if (address(_rewarder) != address(0)) {
_rewarder.onTokenReward(pid, msg.sender, to, 0, user.amount);
}
lpToken[pid].safeTransfer(to, amount);
emit Withdraw(msg.sender, pid, amount, to);
}
/// @notice Harvest proceeds for transaction sender to `to`.
/// @param pid The index of the pool. See `poolInfo`.
/// @param to Receiver of Token rewards.
function harvest(uint256 pid, address to) public {
PoolInfo memory pool = updatePool(pid);
UserInfo storage user = userInfo[pid][msg.sender];
int256 accumulatedRewards = int256(user.amount.mul(pool.accRewardPerShare) / ACC_PRECISION);
uint256 _pendingRewards = accumulatedRewards.sub(user.rewardDebt).toUInt256();
// Effects
user.rewardDebt = accumulatedRewards;
// Interactions
if (_pendingRewards != 0) {
rewardToken.safeTransferFrom(rewardOwner, to, _pendingRewards);
}
IRewarder _rewarder = rewarder[pid];
if (address(_rewarder) != address(0)) {
_rewarder.onTokenReward(pid, msg.sender, to, _pendingRewards, user.amount);
}
emit Harvest(msg.sender, pid, _pendingRewards);
}
/// @notice Withdraw LP tokens from Staking contract and harvest proceeds for transaction sender to `to`.
/// @param pid The index of the pool. See `poolInfo`.
/// @param amount LP token amount to withdraw.
/// @param to Receiver of the LP tokens and Token rewards.
function withdrawAndHarvest(
uint256 pid,
uint256 amount,
address to
) public {
PoolInfo memory pool = updatePool(pid);
UserInfo storage user = userInfo[pid][msg.sender];
int256 accumulatedRewards = int256(user.amount.mul(pool.accRewardPerShare) / ACC_PRECISION);
uint256 _pendingRewards = accumulatedRewards.sub(user.rewardDebt).toUInt256();
// Effects
user.rewardDebt = accumulatedRewards.sub(int256(amount.mul(pool.accRewardPerShare) / ACC_PRECISION));
user.amount = user.amount.sub(amount);
// Interactions
rewardToken.safeTransferFrom(rewardOwner, to, _pendingRewards);
IRewarder _rewarder = rewarder[pid];
if (address(_rewarder) != address(0)) {
_rewarder.onTokenReward(pid, msg.sender, to, _pendingRewards, user.amount);
}
lpToken[pid].safeTransfer(to, amount);
emit Withdraw(msg.sender, pid, amount, to);
emit Harvest(msg.sender, pid, _pendingRewards);
}
/// @notice Withdraw without caring about rewards. EMERGENCY ONLY.
/// @param pid The index of the pool. See `poolInfo`.
/// @param to Receiver of the LP tokens.
function emergencyWithdraw(uint256 pid, address to) public {
UserInfo storage user = userInfo[pid][msg.sender];
uint256 amount = user.amount;
user.amount = 0;
user.rewardDebt = 0;
IRewarder _rewarder = rewarder[pid];
if (address(_rewarder) != address(0)) {
_rewarder.onTokenReward(pid, msg.sender, to, 0, 0);
}
// Note: transfer can fail or succeed if `amount` is zero.
lpToken[pid].safeTransfer(to, amount);
emit EmergencyWithdraw(msg.sender, pid, amount, to);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor() {
_setOwner(_msgSender());
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
_setOwner(address(0));
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_setOwner(newOwner);
}
function _setOwner(address newOwner) private {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../IERC20.sol";
import "../../../utils/Address.sol";
/**
* @title SafeERC20
* @dev Wrappers around ERC20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeERC20 {
using Address for address;
function safeTransfer(
IERC20 token,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(
IERC20 token,
address from,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(
IERC20 token,
address spender,
uint256 value
) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender) + value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
unchecked {
uint256 oldAllowance = token.allowance(address(this), spender);
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
uint256 newAllowance = oldAllowance - value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
// Return data is optional
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./Address.sol";
/**
* @dev Provides a function to batch together multiple calls in a single external call.
*
* _Available since v4.1._
*/
abstract contract Multicall {
/**
* @dev Receives and executes a batch of function calls on this contract.
*/
function multicall(bytes[] calldata data) external returns (bytes[] memory results) {
results = new bytes[](data.length);
for (uint256 i = 0; i < data.length; i++) {
results[i] = Address.functionDelegateCall(address(this), data[i]);
}
return results;
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.8.4;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
interface IRewarder {
function onTokenReward(uint256 pid, address user, address recipient, uint256 tokenAmount, uint256 newLpAmount) external;
function pendingTokens(uint256 pid, address user, uint256 tokenAmount) external view returns (IERC20[] memory, uint256[] memory);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.8.4;
/// reference: https://github.com/boringcrypto/BoringSolidity/blob/master/contracts/libraries/BoringMath.sol
/// changelog: renamed "BoringMath" => "SafeMath"
/// @notice A library for performing overflow-/underflow-safe math,
/// updated with awesomeness from of DappHub (https://github.com/dapphub/ds-math).
library SafeMath {
function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
require((c = a + b) >= b, "SafeMath: Add Overflow");
}
function sub(uint256 a, uint256 b) internal pure returns (uint256 c) {
require((c = a - b) <= a, "SafeMath: Underflow");
}
function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
require(b == 0 || (c = a * b) / b == a, "SafeMath: Mul Overflow");
}
function to128(uint256 a) internal pure returns (uint128 c) {
require(a <= type(uint128).max, "SafeMath: uint128 Overflow");
c = uint128(a);
}
function to64(uint256 a) internal pure returns (uint64 c) {
require(a <= type(uint64).max, "SafeMath: uint64 Overflow");
c = uint64(a);
}
function to32(uint256 a) internal pure returns (uint32 c) {
require(a <= type(uint32).max, "SafeMath: uint32 Overflow");
c = uint32(a);
}
}
/// @notice A library for performing overflow-/underflow-safe addition and subtraction on uint128.
library SafeMath128 {
function add(uint128 a, uint128 b) internal pure returns (uint128 c) {
require((c = a + b) >= b, "SafeMath: Add Overflow");
}
function sub(uint128 a, uint128 b) internal pure returns (uint128 c) {
require((c = a - b) <= a, "SafeMath: Underflow");
}
}
/// @notice A library for performing overflow-/underflow-safe addition and subtraction on uint64.
library SafeMath64 {
function add(uint64 a, uint64 b) internal pure returns (uint64 c) {
require((c = a + b) >= b, "SafeMath: Add Overflow");
}
function sub(uint64 a, uint64 b) internal pure returns (uint64 c) {
require((c = a - b) <= a, "SafeMath: Underflow");
}
}
/// @notice A library for performing overflow-/underflow-safe addition and subtraction on uint32.
library SafeMath32 {
function add(uint32 a, uint32 b) internal pure returns (uint32 c) {
require((c = a + b) >= b, "SafeMath: Add Overflow");
}
function sub(uint32 a, uint32 b) internal pure returns (uint32 c) {
require((c = a - b) <= a, "SafeMath: Underflow");
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.8.4;
library SignedSafeMath {
int256 constant private _INT256_MIN = -2**255;
/**
* @dev Returns the multiplication of two signed integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
*
* - Multiplication cannot overflow.
*/
function mul(int256 a, int256 b) internal pure returns (int256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) {
return 0;
}
require(!(a == -1 && b == _INT256_MIN), "SignedSafeMath: multiplication overflow");
int256 c = a * b;
require(c / a == b, "SignedSafeMath: multiplication overflow");
return c;
}
/**
* @dev Returns the integer division of two signed integers. Reverts on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(int256 a, int256 b) internal pure returns (int256) {
require(b != 0, "SignedSafeMath: division by zero");
require(!(b == -1 && a == _INT256_MIN), "SignedSafeMath: division overflow");
int256 c = a / b;
return c;
}
/**
* @dev Returns the subtraction of two signed integers, reverting on
* overflow.
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(int256 a, int256 b) internal pure returns (int256) {
int256 c = a - b;
require((b >= 0 && c <= a) || (b < 0 && c > a), "SignedSafeMath: subtraction overflow");
return c;
}
/**
* @dev Returns the addition of two signed integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
*
* - Addition cannot overflow.
*/
function add(int256 a, int256 b) internal pure returns (int256) {
int256 c = a + b;
require((b >= 0 && c >= a) || (b < 0 && c < a), "SignedSafeMath: addition overflow");
return c;
}
function toUInt256(int256 a) internal pure returns (uint256) {
require(a >= 0, "Integer < 0");
return uint256(a);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
assembly {
size := extcodesize(account)
}
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}